Making rosemary-infused olive oil is simple. Place the oil and rosemary sprigs in a saucepan and heat over low heat for 6 to 8 minutes. You want to get the oil warm enough to begin the infusion process. Let the oil cool to room temperature before filling the bottles. Make sure there’s enough fresh rosemary sprigs to adorn the number of bottles you have. Place one rosemary sprig into each before pouring the infused oil into the bottle for a more decorative DIY gift. Make sure to clean and completely dry the sprigs overnight before placing them in the bottle—bacteria can’t grow in the oil itself, but it can grow in the water left back on the herbs. You can also add some red pepper flakes if you know your friends prefer oil that packs a bit of heat. And if rosemary isn’t your thing, try a different herb like thyme or sage.